Misplaced Pages

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35-416: The highway is now little used and poorly maintained, and closed to all traffic from October to mid-May each year. Only the easternmost 21.3 miles (34.3 km) and westernmost 2.6 miles (4.2 km) are paved; whether the remainder should be paved as well is a continual source of debate. Washboarding and extreme dust are common, and the recommended speed limit is 30 mph (48 km/h). Traveling west,

70-421: A dense, tight mass with an almost impervious surface ." It emphasizes the proper gradation of gravel—100% passing the 0.75 inches (19 mm)) sieve—to have fractured stone to "interlock" and 4–15% fines passing the #200 (75-μm) sieve to act as a binder and create cohesiveness in the gravel; substituting other binders, such as clay is also recommended. Alternately, one can incorporate reclaimed asphalt in

105-581: A discharge tube to formation of striations with regular or random character. When a planar body of fluid under the influence of gravity is heated from below, Rayleigh-Bénard convection can form organized cells in hexagons or other shapes. These patterns form on the surface of the Sun and in the mantle of the Earth as well as during more pedestrian processes. The interaction between rotation, gravity, and convection can cause planetary atmospheres to form patterns, as

140-459: A field sensing and responding to its position along a morphogen gradient, followed by short distance cell-to-cell communication through cell signaling pathways to refine the initial pattern. In this context, a field of cells is the group of cells whose fates are affected by responding to the same set positional information cues. This conceptual model was first described as the French flag model in

175-439: A half-and-half blend with quarried gravel to improve the binding properties of the surface. For existing washboarded surfaces, the bulletin recommends using a grader to cut and blend existing material to a depth one inch or more below the bottom of the washboarded segment and then add the new material into the top layer. Useful equipment includes a blade with rotating scarifying teeth or a replaceable bit-type cutting edge attached to

210-450: A little patience, by repeatedly sharpening and blurring an image in a graphics editor. If other filters are used, such as emboss or edge detection , different types of effects can be achieved. Computers are often used to simulate the biological, physical or chemical processes that lead to pattern formation, and they can display the results in a realistic way. Calculations using models like reaction–diffusion or MClone are based on

245-484: A series of ripples, which occur with the passage of wheels rolling over unpaved roads at speeds sufficient to cause bouncing of the wheel on the initially unrippled surface and take on the appearance of a laundry washboard . Most studies of washboarding pertain to granular materials, including sand and gravel . However, other work suggests that the phenomenon may occur in material which has some binding of particles, e.g. clay-like soils . Highway department experts in

280-415: A variety of granular and viscous, even fluid, materials. In the laboratory, washboarding has been studied for a range of parameters, including the thickness and grain size of the material for varied wheel sizes, shapes, and masses. Experiments produced ripples for each parameter, above a threshold speed, when the wheel (or blade) began to bounce. Experiments also show that the pattern can move either against

315-693: Is driven by positive feedback loops between local vegetation growth and water transport towards the growth location. Pattern formation has been well studied in chemistry and chemical engineering, including both temperature and concentration patterns. The Brusselator model developed by Ilya Prigogine and collaborators is one such example that exhibits Turing instability . Pattern formation in chemical systems often involve oscillatory chemical kinetics or autocatalytic reactions such as Belousov–Zhabotinsky reaction or Briggs–Rauscher reaction . In industrial applications such as chemical reactors, pattern formation can lead to temperature hot spots which can reduce

350-666: Is seen in Saturn's hexagon and the Great Red Spot and stripes of Jupiter . The same processes cause ordered cloud formations on Earth, such as stripes and rolls . In the 1980s Lugiato and Lefever developed a model of light propagation in an optical cavity that results in pattern formation by the exploitation of nonlinear effects. Precipitating and solidifying materials can crystallize into intricate patterns, such as those seen in snowflakes and dendritic crystals . Sphere packings and coverings. Mathematics underlies

385-472: Is the formation of periodic, transverse ripples in the surface of gravel and dirt roads . Washboarding occurs in dry, granular road material with repeated traffic, traveling at speeds above 8.0 kilometres per hour (5 mph). Washboarding creates an uncomfortable ride for the occupants of traversing vehicles and hazardous driving conditions for vehicles that travel too fast to maintain traction and control. Washboarding or corrugation of roads comprises

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420-465: Is thought to be responsible for the fold patterns on the cerebral cortex of higher animals, among other things. Bacterial colonies show a large variety of patterns formed during colony growth. The resulting shapes depend on the growth conditions. In particular, stresses (hardness of the culture medium, lack of nutrients, etc.) enhance the complexity of the resulting patterns. Other organisms such as slime moulds display remarkable patterns caused by

455-824: The Amphitheater Mountains , cresting at Maclaren Summit, at 4,086 feet (1,245 m) the second highest road in Alaska. The road then drops down to the Maclaren River Valley with fine views north to Maclaren Glacier . After crossing the Maclaren River, the road winds through the geologically mysterious Crazy Notch and then along the toe of the Denali Clearwater Mountains to the Susitna River . After crossing

490-1390: The moldboard blade of the earth-moving equipment. Pattern formation Collective intelligence Collective action Self-organized criticality Herd mentality Phase transition Agent-based modelling Synchronization Ant colony optimization Particle swarm optimization Swarm behaviour Social network analysis Small-world networks Centrality Motifs Graph theory Scaling Robustness Systems biology Dynamic networks Evolutionary computation Genetic algorithms Genetic programming Artificial life Machine learning Evolutionary developmental biology Artificial intelligence Evolutionary robotics Reaction–diffusion systems Partial differential equations Dissipative structures Percolation Cellular automata Spatial ecology Self-replication Conversation theory Entropy Feedback Goal-oriented Homeostasis Information theory Operationalization Second-order cybernetics Self-reference System dynamics Systems science Systems thinking Sensemaking Variety Ordinary differential equations Phase space Attractors Population dynamics Chaos Multistability Bifurcation Rational choice theory Bounded rationality The science of pattern formation deals with

525-430: The 1960s. More generally, the morphology of organisms is patterned by the mechanisms of evolutionary developmental biology , such as changing the timing and positioning of specific developmental events in the embryo. Possible mechanisms of pattern formation in biological systems include the classical reaction–diffusion model proposed by Alan Turing and the more recently found elastic instability mechanism which

560-565: The Denali Highway is exclusively by snowmobile and dogsled. Automobile travelers are severely discouraged from attempting to traverse the road in winter; as recently as 1996 three persons died from exposure when snows blocked their progress. The road is cleared by DOT late in April and generally is passable by non-4WD from then until the first snows close it, usually late September on the eastern, tundra end and late October-early November on

595-706: The Denali Highway leaves the Richardson Highway (Alaska Route 4) at Paxson, and climbs steeply up into the foothills of the central Alaska Range. The first 21 miles (34 km), to Tangle Lakes , are paved. Along its length, the highway passes through three of the principal river drainages in Interior Alaska: the Copper River drainage, the Tanana / Yukon drainage and the Susitna drainage. Along

630-520: The Nevada Department of Highways advocated mitigating corrugations with crushed pit-run gravel, using material 1 inch (25 mm) and smaller, including only the fines from crushing. Contemporaneous advice from Colorado was to use a well-graded gravel, not exceeding 1.25 inches (32 mm) and including 25–40% fines passing a 0.25-inch (6.4 mm) sieve, but not more than 5% passing a #10 (2.0-mm) sieve. The maintenance advice from Colorado

665-1013: The Susitna River the road extends across the glacier's outwash plains to the Nenana River , and then down the Nenana River to Cantwell on the George Parks Highway (Alaska Route 3). There are developed campgrounds at Tangle Lakes (MP 22) and Brushkana Creek (MP 104), but there are dozens of pullouts where one can camp on public lands. Services are scant along this road. Year-round operations include Denali Highway Cabins & Tours (MP 0.2), Maclaren River Lodge (MP 42), Alpine Creek Lodge (MP68), Backwoods Lodge (MP134) and Cantwell Lodge (MP138); summer-only operations include Tangle Lakes Lodge (MP 22), Tangle River Inn (MP 20), Clearwater Mountain Lodge (MP 82). Winter travel on

700-407: The animals may be competing with hunters. The many lakes along the road are also a destination for duck hunting in the fall. Most of the land along the highway is publicly owned. There are several BLM-maintained trails, and dozens of informal trails. This is a stretch of wild Alaska that is pretty much unspoiled, relatively accessible and scenic. Washboarding Washboarding or corrugation

735-549: The bare zone immediately above it. In contrast, fir waves occur in forests on mountain slopes after wind disturbance, during regeneration. When trees fall, the trees that they had sheltered become exposed and are in turn more likely to be damaged, so gaps tend to expand downwind. Meanwhile, on the windward side, young trees grow, protected by the wind shadow of the remaining tall trees. In flat terrains additional pattern morphologies appear besides stripes - hexagonal gap patterns and hexagonal spot patterns. Pattern formation in this case

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770-513: The direction of motion or in the direction of motion. They also show that a passive, non-driving wheel suffices to create corrugations and that displacement of material, rather than ejection, is the dominant mechanism. Several articles about real-life washboarding on roads cite South Dakota Local Transportation Assistance Program (LTAP) Special Bulletin #29, “Dealing with Washboarding,” by Ken Skorseth. Those sources attribute washboarding to three causes: dry granular materials, vehicle speeds, and

805-422: The dynamics of chemical signaling. Cellular embodiment (elongation and adhesion) can also have an impact on the developing patterns. Vegetation patterns such as tiger bush and fir waves form for different reasons. Tiger bush consists of stripes of bushes on arid slopes in countries such as Niger where plant growth is limited by rainfall. Each roughly horizontal stripe of vegetation absorbs rainwater from

840-690: The lakes and ponds along the route. Fishing for grayling and lake trout is possible in any of the clear and unglaciated streams. Because the area is hunted heavily, larger mammals are much less common than in Denali National Park, but moose, grizzly bear, and caribou are fairly common. The Nelchina caribou herd, approximately 36,000 animals as of winter 2009–2010, normally passes through this area after calving season ends, and some autumns and winters as many as 16,000 animals can be seen at once. The herd forms an important foodsource for many residents of southcentral Alaska, and visitors eager to view

875-924: The lower, boreal forest western end. The Tangle Lakes constitute the headwaters of the Delta River , a popular destination for canoeists as it is the launch point of the Delta River Canoe Trail . The Denali Highway is an important birding destination. It offers road access to alpine terrain – not that common in Alaska – and, in the brief birding season there, good viewing of a number of alpine breeders, including Arctic Warbler , Smith's Longspur , Long-tailed Jaeger , Whimbrel , Surfbird , Lapland Longspur , Horned Lark , Short-eared Owl , Wandering Tattler , Gyrfalcon and much more. A walk north along The Bureau of Land Management's (BLM) Maclaren Summit Trail (MP 39) can be very productive. There are also trumpeter swans and various other waterfowl in

910-399: The mid-1920s were aware that traffic volume and speed were primary causes of corrugations on gravel roads and cited the role of drive wheels tossing material as a factor. Laboratory-scale studies of the phenomenon typically employ a wheel or a blade, which is towed behind a pivot point, tracing a circular path through a pan of the material under examination. These studies have investigated

945-465: The other pattern formation mechanisms listed. Some types of automata have been used to generate organic-looking textures for more realistic shading of 3d objects . A popular Photoshop plugin, KPT 6 , included a filter called 'KPT reaction'. Reaction produced reaction–diffusion style patterns based on the supplied seed image. A similar effect to the 'KPT reaction' can be achieved with convolution functions in digital image processing , with

980-421: The quality of the granular material. Other factors cited include vehicle speed, traffic volume, and hard acceleration or braking. The sources also claim that light vehicles are more likely to cause washboarding than heavy trucks. Highway department guidance suggests that choice of gravel can be key to mitigating washboarding. They cite "sieve analysis" tests that use a series of screens or sieves to characterize

1015-601: The science of evolutionary developmental biology or evo-devo. The mechanisms involved are well seen in the anterior-posterior patterning of embryos from the model organism Drosophila melanogaster (a fruit fly), one of the first organisms to have its morphogenesis studied, and in the eyespots of butterflies, whose development is a variant of the standard (fruit fly) mechanism. Examples of pattern formation can be found in biology, physics, and science, and can readily be simulated with computer graphics, as described in turn below. Biological patterns such as animal markings ,

1050-444: The segmentation of animals, and phyllotaxis are formed in different ways. In developmental biology , pattern formation describes the mechanism by which initially equivalent cells in a developing tissue in an embryo assume complex forms and functions. Embryogenesis , such as of the fruit fly Drosophila , involves coordinated control of cell fates . Pattern formation is genetically controlled, and often involves each cell in

1085-413: The sizes of particles contained within a gravel sample. Highway department guidance suggests a range of particle sizes from stones that are in the 1-inch (25 mm) range, mixed with progressively finer particles to include a small fraction of fine particles that bind the larger particles together. They also mention the role of equipment that can re-blend and smooth surfaces that have corrugated. In 1925,

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1120-416: The visible, ( statistically ) orderly outcomes of self-organization and the common principles behind similar patterns in nature . In developmental biology , pattern formation refers to the generation of complex organizations of cell fates in space and time. The role of genes in pattern formation is an aspect of morphogenesis , the creation of diverse anatomies from similar genes, now being explored in

1155-620: The way, in good weather, there are views of the peaks and glaciers of the central Alaska Range, including Mount Hayes (13,700 ft), Mount Hess (11,940 ft) and Mount Deborah (12,688 ft). At MP 15, from the pullout on the south side of the road, in clear weather it is possible to see the Wrangell Mountains , the Chugach Mountains and the Alaska Range . The first 45 miles (72 km) winds through

1190-539: The yield or create hazardous safety problems such as a thermal runaway . The emergence of pattern formation can be studied by mathematical modeling and simulation of the underlying reaction-diffusion system . Similarly as in chemical systems, patterns can develop in a weakly ionized plasma of a positive column of a glow discharge. In such cases creation and annihilation of charged particles due to collisions of atoms corresponds to reactions in chemical systems. Corresponding processes are essentially non-linear and lead in

1225-407: Was to drag or grade the road frequently, applying light volumes of new gravel with minimal sand content and providing good drainage with a crown. The same source advises reduction of traffic speed. Guidance based on South Dakota LTAP Special Bulletin #29 and FHWA guidance (2000) from the same source suggests that the surface gravel "should be a blend of stone, sand and fines that will compact into

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